1. Field of the Invention
The present invention relates to a method and apparatus for treating electrically conductive fluid, that is fluid having some electroconductive capability. More particularly, the present invention relates to a self-generating apparatus using electrodes located externally of a fluid passageway to ionize the fluid as the fluid passes through the passageway.
2. Description of the Related Art
Self-energizing fluid treatment devices which employ electrodes of electrically conductive materials having different electrochemical potentials are known. The term self-energizing refers to the fact that these devices employ no external power source. In these devices, the fluid to be treated flows over the electrodes whereby an electroconductive connection between the electrodes is established through the body of flowing fluid. In some of these devices, the electrodes pose a significant obstruction to the fluid flow. Further, because the electrodes are exposed to the fluid flow, the electrodes are abraded and/or worn to a considerable extent particularly when the fluid entrains non-soluble particles. Still further, depending on the nature of the fluid, the electrically conductive materials of the electrodes may corrode due to electrolysis.
One of the known self-generating devices having electrodes of different electrochemical potentials is disclosed in U.S. Pat. No. 5,234,555. In this device, the electrically conductive materials of the electrodes are provided with an electrically insulative coating to isolate the fluid from the electrically conductive materials of the electrodes. Several years of research by the present inventor had revealed that an ideal condition for fluid treatment is a voltage potential only condition between the electrodes. The inhibition of current flow through the fluid to an absolute minimum is necessary in establishing this condition. The coating of the electrode(s) with an electrically insulative material as disclosed in U.S. Pat. No. 5,234,555 to be an efficient and reliable means to achieve the above-mentioned voltage potential only condition.
The plastics used as the coatings of the electrodes are known to be imperfect as electric insulators and accordingly, electrons will always pass through the plastic however small such leakage may be. Even a minimal amount of electrons is sufficient for a voltage potential to develop between electrodes of different electrochemical potentials. Again, research by the present inventor has shown that as the current flow through the fluid is reduced and the voltage potential only condition is maintained, the treatment of the fluid becomes more efficient.
However, the coated electrodes are still disposed within the line of fluid flow. Thus, the device suffers from the problems described above. Specifically, the plastic coating is worn and abraded away, particularly by industrial water in which solid particles are suspended, thereby exposing the electrode to the fluid with the resultant loss in efficiency. This problem cannot be effectively overcome by increasing the thickness of the coating because this countermeasure in turn gives rise to problems such as reducing the flow area and increasing manufacturing costs.
Although it is known in the prior art to keep the electrodes out of contact with the fluid flow, the electrodes are nonetheless connected to an external electric power supply. In this case, the electrically conductive materials of the electrodes do not need to have different electrochemical potentials.